The effect of hallux abducto valgus surgery on the sesamoid apparatus position.

A new parameter, the tibial sesamoid-second metatarsal distance, was established to determine whether the sesamoids move in relation to the foot in hallux abducto valgus surgery. The reliability of the tibial sesamoid-second metatarsal distance was assessed and shown to be excellent. Seventy-five feet underwent surgical correction of hallux abducto valgus. Four radiographic parameters--the intermetatarsal angle, the hallux abductus angle, the tibial sesamoid position, and the tibial sesamoid-second metatarsal distance--were measured before and after surgery. The hallux abductus angle, intermetatarsal angle, and tibial sesamoid position were all significantly reduced following surgery. The tibial sesamoid-second metatarsal distance was not affected by hallux abducto valgus correction. Thus the correction in sesamoid position gained with hallux abducto valgus correction is a direct result of lateral translocation of the metatarsal head, with no contribution from change in position of the sesamoid apparatus relative to the foot.